1. Field of the Invention
The present invention is related to a method of forming a fine pattern by using phase separation of a block copolymer, and to a developing solution that can be used in the method.
This application claims priority to Japanese Patent Application No. 2012-145474 filed on Jun. 28, 2012, and the content of which is incorporated herein by reference.
2. Description of Related Art
Recently, as further miniaturization of large scale integrated circuits (LSI) proceeds, technology for forming an even finer pattern is demanded. In response to such demand, a method has been disclosed in which a fine pattern is formed using a phase-separated structure formed by self-assembly of a block copolymer having mutually incompatible blocks bonded together (see, for example, Patent Document 1).
For using a phase separation of a block copolymer, it is necessary to form a self-organized nano structure by a microphase separation only in specific regions, and arrange the nano structure in a desired direction. For realizing position control and orientation control, graphoepitaxy to control phase-separated pattern by a guide pattern and chemical epitaxy to control phase-separated pattern by difference in the chemical state of the substrate are proposed (see, for example, Non-Patent Document 1).
Methods for selectively removing a specific block region from a nano phase separated structure of a block copolymer are classified mainly into a liquid phase-type method and a dry-type method (see, for example, Non-Patent Document 2). The dry-type method (dry etching) is a method in which a reactive gas is blown on the nanophase-separated structure, and selective removal is conducted by using the difference in the decomposition rate of the polymers by the dry gas. On the other hand, the liquid phase-type method (liquid etching) is a method in which a block in a specific block region of the nanophase-separated structure is selectively decomposed if desired, followed by immersing the nanophase-separated structure in a developing solution, so as to preferentially dissolve and remove a specific phase portion. In the liquid etching, developing solutions based on aqueous solutions have generally been used, because materials thought to be formed by decomposition of the block is highly soluble to aqueous solutions.
Nano structures formed by using phase separation of the block copolymer as described above have been widely used as masks for conducting etching of supports (substrates). Usually, dry etching which uses reactive gas is applied for etching of supports.